Customer referrals are, hands-down, the most profitable source of new business. They are vastly more credible than any advertisement, email or press release your company might generate.

Here are dozens of proven ways to get your customers to recommend your company to their friends.

How to ask for a referral: According to Jill Griffin, loyalty expert, you should say, “Who do you know that might appreciate knowing about my services?” After you get the first name, say, “Who else do you know?” Repeat the process until your client runs out of names.

Special discount: Customer gets a 5% discount on their next order for a referral.

Discount times two: Customer and friend get a 5% discount on their next order.

Discount times two, making the customer look good: Invisible Fence, which protects dogs by outfitting them with collars that keep them in their yards, offers free collar batteries for a year to any customer who refers a new fence customer. The company then sends a $100 gift certificate in the customer’s name to the prospect.

Birthday/special event celebrations: Host an event for a customer on special occasion. This causes them to invite others.

Women’s (or men’s) nights: Bring two others and get special privileges or prices.

Send a catalog to a friend: Whenever you take orders from customers (i.e. order forms, catalogs, etc.) provide a space in which they can instruct you to send information to a friend or colleague.

Affinity programs: Get special interest groups to align themselves with your offerings (think: Sierra Club MasterCard). The group gets a new income stream; you get the ability to attract people with strong special interests.

Support fundraising efforts: Offer services to non-profit groups and schools at a discount, so that they can resell them at a profit to support their programs.

Thank you letters: Send a thank you letter to a customer just after their order has been delivered. Feel free to ask whether they know of others who would give you the privilege to serve them.

Compensate employees: Offer a special incentive to employees who refer their friends to their company.

Referral list: Maintain a list of customers who are happy to be called by prospective customers.

Donut patrol: Drop off doughnuts, candy, fruit baskets or the like to valuable customers. The more dramatic and notable the present, the better. They’re likely to tell others what a unique firm you have.

Digital gifts: Send customers – and prospects – highly useful information in digital form. Make it valuable enough that they are likely to share it with others. (The document you are now reading uses this strategy.)

Free booklets: Provide concise handbooks to customers. Send them one extra for a friend.

Referral cards: Personalize cards for highly valuable customers (perhaps with a photo of the customer and the pool/house/painting/new deck/etc. you sold her.) She can use the cards as an easy way to refer you to a friend and ensure she gets the benefits you offer customers for referrals.

Customer ratings: Encourage customers to rate your products/services publicly (i.e. at your web site) and share these ratings with others. This has some risk, but it shows you have nothing to hide and puts pressure on your team to be ultra-responsive to customers.

Reference letters: Collect letters from delighted customers and post them on your walls, post them on your web site, and include them in prospect mailings.

Insiders Club: Offer special events and/or privileges to customers who generate a certain threshold of referrals. For example, you might hold a special party or invite customers to a sporting event.

VIP service: Offer faster, better service to customers in exchange for referrals.

Free newsletters: Send email newsletters to customers, and make them easy to forward. Include a link at the bottom that makes it easy for someone to sign up for the newsletter after receiving it from a friend.

Share the love: When the press writes about you, send copies to good customers and include an envelope and/or sticky note that makes it easy for them to send the article on to a friend.

Birthday/Anniversary cards: Send one to your customers, along with an incentive to refer a friend.

Share the fame: With permission, give credit to customers for better ways to use your products or solve problems your customers share.

Share the photos: Publish pictures of your customers. The world’s largest dairy store operator, Stew Leonards, encourages customers to photograph themselves holding a Stew’s shopping bag at notable places around the word. You can find these photos in the stores, and now you can find bags from this Connecticut retailer all around the world.